A syndesmotic injury results when a traumatic injury damages the ligaments that span the gap between the distal tibia and fibula. This can be the result of a high ankle sprain, with no fracture of the fibula, or can also accompany a fibular fracture in a Weber B or Weber C fracture.
A surgeon can determine the presence of a syndesmotic injury by direct visualization of the joint or through radiographic imaging while positioning the ankle in a mortise view orientation. In either case, loads are applied to the joint in either a direct lateral load applied to the fibula or by applying an external rotation load to the foot. While the load is being applied, the relative distance between the fibula and the tibia, the fibula and the talus, and the tibia and the talus are observed to determine the level of damage sustained by the ligaments that typically hold the syndesmotic joint together.
If a syndesmotic injury is found to be present, the typical treatment involves stabilizing the fibula and tibia with respect to each other in the proper orientation and holding them there throughout the soft tissue healing period to allow the ligaments to re-attach and heal. In the event of a syndesmotic injury with a corresponding fibula fracture, this is done while also stabilizing the fibular fracture, which is usually accomplished with a small fracture plate on the lateral side of the fibula. Traditionally the method of stabilization has been to place one or more cortical screws across the syndesmosis, with the head against the lateral face of the fibula and the tip of the screw being in the middle of the tibia or in the medial cortex of the tibia, e.g., as shown in FIG. 1.
This form of treatment provides very rigid fixation, allowing the ligaments to heal, but makes return to weight-bearing more difficult. During a standard gait, the ligaments hold the distance between the tibia and fibula fairly constant, but allow a small amount of shear motion and rotation of the fibula with respect to the tibia. The presence of the fixation screws prevents this motion and can cause discomfort and limited flexibility of the ankle joint. Typically, the surgeon prescribes a secondary surgery to remove the screws once the ligaments have healed. In some cases, a surgeon may simply recommend a return to weight-bearing when the ligaments have healed and, after a period of time of loading the screws, they will experience a fatigue failure and normal anatomical motion will be restored.
Accordingly, apparatus and methods for providing semi-rigid fixation of the distal tibia and fibula following a syndesmotic injury would be useful.